Honor Level 0, 0 checkpoints, but not even a chat restrict for over 6 months.
I'm pretty sure Riot have made it impossible to actually get back up to honor level 2 within the same season as you reach honor level 0. Honor level 4 probably takes all of 2 weeks for someone to hit if they've never been punished, but it really does seem like Riot want to intentionally promote toxic behavior by saying, "you're toxic and you'll never be anything but toxic"
Keep in mind that getting chat restricted ever automatically drops you to honor level 0.